Fuel oil compositions



United States Patent 3,415,632 FUEL OIL COMPOSITIONS Alois Rechberger, Vienna, Austria, assignor to Shell Oil Company, New York, N.Y., a corporation of Delaware No Drawing. Filed May 31, 1966, Ser. No. 553,677 Claims priority, application Austria, June 4, 1965, A 5,121/65 2 Claims. (CI. 44-74) ABSTRACT OF THE DISCLOSURE A fuel oil composition containing a combination of cyclohexyl nitrate and an oil soluble barium salt of a sulfonic acid to inhibit exhaust smoke emission.

This invention relates to fuel oil compositions having improved combustion characteristics. More particularly, the invention relates to diesel fuels containing anti-smoke additives.

The problem of the exhaust gases from engines operating with hydrocarbon fuels has become increasingly serious, particularly in view of the mounting problems of air pollution and smog and imminent restrictive legislation. Diesel engines are heavy contributors to pollution, often spewing black noxious exhaust gases into the atmosphere. A method of reducing the amount of exhaust smoke from these road vehicles would obviously be very desirable.

It is known that exhaust smoke may be reduced in diesel engine vehicles by using fuels containing certain antismoke additives. Additives of this kind may be, for example, salts of petroleum sulfonic acids, such as described in US. Patent 3,085,866, issued Apr. 16, 1963, to Gay et al. It is also known that the ignition properties of fuels can be improved by the addition of certain ignition accelerators such as some organic nitrates.

It has now been found that certain organic nitrates and certain oil-soluble alkaline earth metal salts of organic acids unexpectedly cooperate with respect to antismoke effect when added in combination to liquid hydrocarbon fuels. Accordingly, the invention is directed to improved hydrocarbon fuels, such as diesel fuel mixtures, having low smoking tendencies, characterized in that they contain certain organic nitrates and a oil-soluble earth metal salt of an organic acid.

The base fuel for use in accord with the invention may be any fuel oil, such as gas oil, distillate oil, or furnace oil, but is preferably an oil which boils in the kerosene and gas oil ranges.

Preferred organic nitnates are substituted or unsubstituted alkyl or cycloalkyl nitrates having up to ten carbon atoms, preferably from four to ten carbon atoms. Especially preferred additives are esters of cycloaliphatic alcohols, such as cyclohexylnitrate, and esters of alkoxysubstituted aliphatic alcohols, such as l-methoxypropyl-Z nitrate. The preferred additive is cyclohexylnitrate. Examples of other useful compounds are isoamyl nitrate, 2- ethylhexyl nitrate, methylcyclohexyl nitrate, isopropylcyclohexyl nitrate, 1-ethoxypropyl-2-nitrate, l-isopropoxybutyl nitrate, and l-ethoxybutyl nitrate.

Preferred alkaline earth metal salts of organic acids are salts of sulfonic, alkylsalicylic, and naphthenic acids. Sul- 3,415,632 Patented Dec. 10, 19 68 fonic acids may be alkylarylsulfonic acids, such as alkylsubstituted aromatic sulfonic acids, and petroleum sulfonic acids. In general, these acids contain less than 20 carbons per molecule. The term petroleum sulfonic acid includes such acids as are obtained by treatment of aromatic mineral oil fractions with sulfuric acid or S0 Preferred sulfonic acid salts are alkaline earth metal salts having an excess of basicity, i.e., salts containing more than one equivalent of metal per sulfonic acid group. Preferred alkali metals are barium and calcium, especially barium.

Preferred salts of alkylsalicylic acids have one to two alkyl groups, each containing from ten to twenty carbon atoms, preferably twelve to eighteen carbon atoms. As with the sulfonic acids described above, basic salts are preferred, i.e., salts which contain more than one equivalent of metal per carboxyl group.

The term naphthenic acid salts is intended to include alkaline earth metal salts of naphthenic acids which are obtained by refining petroleum fractions, such as lubricating oil distillates. Again, preference is given to basic salts, i.e., salts containing more than one equivalent of metal per acid group.

The organic nitrate additive is used in amounts of 0.01 to 1% by weight of the total fuel composition. Preferred amounts are between 0.05% to 0.15% by weight of the additive. Amounts below the lower limit are usually insufficient for the purpose added, and amounts above the maximum specified amounts are generally unnecessary, although higher and lower amounts may be used. The amount of metal salt is generally used in amounts of from 0.01% to 0.2% by weight of metal based on the total fuel composition. Preferred fuels contain from 0.05% to 0.1% by weight of metal. If both additives are used within the range specified, a cooperative effect of the additives is obtained in reducing the amount of smoke emitted. Generally preferred ratios of nitrate to metal in the fuel are from about 1 to about 25.

The cooperative effect of the additives of the invention are illustrated in the following examples.

EXAMPLE I A diesel fuel having a density of D =0.850, a cetane number of 49, a sulfur content of 0.25 by weight, an I.B.P. of 200 C. and a boiling point of 350 C. was tested in a Saurer 6-cylinder diesel engine. The exhaust smoke emission was compared with the following fuels A, B and C, which were compounded on the same base fuel.

(A) Base fuel +0.1% by weight of cyclohexyl nitrate.

(B) Base fuel +0.25% by weight of an oil concentrate of 22.5% by weight of barium of a 1300% basic barium salt of petroleum sulfonic acids having a molecular weight of 450.

(C) Base fuel +01% by weight of cyclohexyl nitrate and 0.25% by weight of a concentrate in oil to 22.5% by weight of barium of a 1300% basic barium salt of petroleum sulfonic acids having a molecular weight of 450.

The diesel engine was a 200 H.P. 6-cylinder 4-stroke direct-injection engine, type 4F, bore 123 mm., stroke mm., swept volume 10 liters, compression ratio 1:17,

torque 66 kmg. at 1200 to 1600 rpm. The maximum engine speed was 2400 rpm. During the tests the engine was run at a speed of 2200 rpm, corresponding to an output of 190 H.P. The exhaust gases were determined in 21 Bosch Smoke tester in which 330 ml. of exhaust gas were passed through a paper filter. The amount of smoke emitted is expressed as the Percentage of blackening appearing on the filter paper.

The results obtained with the base fuel and with the fuels A to C are presented in Table I.

TABLE I Exhaust smoke in 6-cylinder Saurer diesel at 190 HP.

Exhaust smoke emission percent Fuel blackening of paper filter (Bosch) Base fuel 58 A 58 B 37 C 18 Thus it is apparent that the nitrate additive itself does not affect smoke emission, but nevertheless is remarkably eifective in increasing the efiicacy of the known smoke inhibitor.

EXAMPLE II Corresponding tests were carried out with a Gardner single-cylinder diesel injection engine with a bore of 108 mm., a stroke of 152.4 mm. and a swept volume of 1.4 liters. The base fuel was a gas oil with a cetane number of 54. To this fuel were added 0.05 and 0.1% by weight of cyclohexyl nitrate and 0.25% by weight of the same concentrate of a 1300% basic barium salt of a petroleum sulfonic acid as described in Example I. The fuels were tested at an engine speed of 700 r.p.rn. and at loads of 60 lb./sq. in. B.M:E.P. and 90 lb./sq. in. B.M.E.P. The exhaust smoke was measured by means of an illuminometer which gave the percentage of light absorption effected by the exhaust gases 4 The test results are presented in Table II.

TABLE IL- -EXHAUS'I SMOKE IN GARDNER-DIESEL ENGINE AT 700 R.P.M.

Smoke emission, expressed in percent light absorption Fuel 60 lb./ 90 lb sq. in. sq. in. b.m.e.p. b.m.e.p.

Base fuel 23 70 Base fuel+0.05% w. cyclohexyl nitrate 24. 5 69 Base fuel+0.l% w. cyclohexyl nitrate 23. 5 70 Base fuel+0.25% w. barium salt concentrate 22 47. 5 Base fuel+0.05% w. cyclohexyl nitrate+0.25%

W. barium salt concentrate 19. 5 43 Base fuel+O.l% W. cyolohexyl nitrate+0.25%

w. barium salt concentrate l8. 5 40 References Cited UNITED STATES PATENTS 2,031,497 2/ 1936 Marvel 4457 XR 2,151,432 3/1939 Lyons et al. 4468 XR 3,085,866 4/1963 Gay et al. 4457 FOREIGN PATENTS 993,623 6/1965 Great Britain.

DANIEL E. WYMAN, Primary Examiner.

W. I. SHINE, Assistant Examiner.

U.S. Cl. X.R. 

